c incident K− momentum

Nuclear Phy~fics B67 11973) 3 8 1 - 3 9 4 . North-Holland Publhhing C o m p a n y

S T U D Y OF THE I = ]: K ,-:"t'- ELASTIC S C A T T E R I N G FROM THE R E A C T I O N K - p ~ K ~-71"- p,,-'~" AT 4 . 2 5 G e V / c INCIDENT K - MOMENTUM * B. JONGEJANS, R.A. van MELrRS, A.G. TENNER and H. VOORT}IUIS Zeeman.[.aboratorium. Univer~iteit ran ..imsterdan~. .4m~tcrdam. The ,Vctherland~

P.M. tlEINEN, W.J. METZGER. II.G.J.M. TIECKE and R.T. Van de WALLE F.v~i~ch Lahoratoritim, Univcr~itt'it van .Vi/megen, .Vi#net, en. Tile .Vetherland~

Received 29 O c t o b e r 1973

Ah,~lr;ict: Re,~ult,~ un the cl,l,~lric K - ~r " ,wattcring have been obtained frl)m a '~tudy t)l" tile K ~r ,;y~tem in 15(11)1) event,, iff the type K p ~ K - n - w r ~ at a K - b e a m m o m e n t u m t~f 4.25 (;eVh'. 1 h e on-luas"~-shell value,~ ill fh¢ ,.phcrlcal Ilarnll)nlc In,lment,~ ,.)l" tile K n - ,,tattering angtllar di,.tribuliL~n and the K - n - cl,I,.tiC cro',,',; ~cctic.n have bccn obtained by extrapolation ftl tile pit)n pixie. I'roln fJtc,~¢ value,, we de'terlnin~,,d tile ,~- and p-~ave pilate ,.hil't '~,~tll anti iI ;I,~ a Itlnclil~n of the efl'vctive ma,v~ c.f lhc K - , n - ,,.y'qcm betv..ecn thre,qlllld and 1.25 (;t'V/~ "2. I'hc value i,It" 161111i~ ~nlallcl than 17' h~r ;all ma','., valut',, ;ind file e\l,,lcnt't' ill a i'~a.lV¢ ¢allllt,t be neglected. At t.,tK -n -= 1.18 ( ; e V / c 2 there art" f',.~,ll ',l)l,fi~ns ft'Jt lilt' pha'..,c s h i l l s . ( ) n t i l e av~.'i'.lge, tilt_" t ' l t l ~ , ~.to~.'ll~ln ~1| f h t ' ~ /~' ' ¢l.l~tl,.: S f . l t t e i ' l l l g l i v e r lilt' lt'l-t~)n ill' tile elf~.'CflVC Ill.l~,~, ct)llsldercd . l l l l l l l l l l t s It) dI)llrtl\lllldf'..'[~,• 2 . 5 n l h .

I. I t l t r o d u c t i o n Inanexpt~sttreoftIle2mC'L!RNIIBCtoa4.25(;eV/cK

beama

12evts/~b

savnple of the reaction K

p ~Kn

prr +

has been obtained.

{I)

In t h i s p a p e r w e p r e s e n t r e s u l t s o f a n a n a l y s i s o f t h i s s a m p l e w i t h

the purpose of obtaining information

on the K-rr " elastic scattering process. From

the subsample K-p

~ K -rr-~++(1236}.

* Thi,c investigation is supported by the j,)int research prtlgrams of I'.O..M. and Z.W.O.

(2)

382

B. Jonge/ans et al.. I = ~ K - n - elastic scartt, ring

which at small four-momentum transfer is supposedly dominated by one-pion-.exchange, we obtained, using standard extrapolation procedures, values for the total K - rr - elastic cross section as well as an estimate of the s- and p-~,ave K - rr- phase shifts. For a discussion of the experimental details of this experinaent ~ e refer to previous publications ('refs. [ I, 2]). Preliminary results of this study have been reported at the Kiev (1970) (ref. [31) and the Bologna ( l q T I ) (ref. [4 I) conferences. The present paper differs from these reports mainly bv the larger statistics collected since then and by a more detailed analysis *. Our present results are consistent with, results obtained in similar kind of analyses by other authors (refs. [ 6 - 1 6 ] ) . Reaction (2) seems particularly appropriate for the study of the I = ~ Krr scattering since the simuhaneous production of the A +" in principle allows us the possibility to check the basic assumption of one-pion-exchange, as well as the applied extrap,dation procedure at the baryon vertex, by comparing with real rr+p scattering.

2. Methods and results 2. I. T h e c x p e r i , w n t a l d a t a

Tahle I sttnnnarizcs sonic nunlbcrs attd cross sections for the final slates considered in this paper. All cross sections are based upon a nornlalization to the number t~l"7" decays observed in the saute fiducial vohlnle as for the four-prong events. Table I Nunlber o f events ;l[ItJCrilss ~,¢CliOllS

K " p ~ tt~ur-prt~nlzs K -n " p n+

Nutnhcr of events

a(mb) a)

530(14)

4 40 t O. I 0

15127

K-n -A++

1.28 t 0.06 0.40 t 0.04

K - n - p n'+ with 1.14 < ,¢4pn.+ < 1.36 (;eV/c 2

6419

~ - n " p n + with in additic~n

-tK ~ K - n - < 0.4 (GeV/c) 2

2392

a) The cross section for the four-prongs includes tile contribution of tile events with a decaying

K-. The errors combine statistical and systematical effi.'cts.

° The analysis is more fully described in a thesis by one of the authors (rcf. [5]).

B Jongejans et al.. I = 7~ K - n -

elastic scattering

383

8OO

15127 events

~ 60C

0

4o0 Z W bJ

I[ 7

0 10

1,'5

M~.,

20

( O e V / c 2)

Fig. I. The pn + effective ma,,s distrihuti,n (' 15 127 errs). The shaded distrihutitm contains the events with - t K .. -, K -~r " < 0.4 ((;cV/c) z {3728 events). If ;,Iso 1.14 < Mpn4. < 1.36 (;eV/c 2 is required, then 2392 events remain. In order to extract events from reaction ( I ) with tile prr + effective mass lying m tile A ~'' region, tile following c o n d i t i o n is applied: 1.14
('3)

The values chosen correspond to equal c o n t r i b u t i o n s from an experimental Opn÷ Breit-Wigner centered on 1.215 GeV]c 2. Events belonging to reaction (' I ) .satisfy a 4C-fit at tile production vertex. As a consequence our sample is not seriously c o n t a m i n a t e d by events actually coming from a different reaction. Jlowever, for events where both the K - and the rrmesons have a large n l o m e n t u m , the identity o f the negative particles may be ambiguous. This is the case for 9.0"I, of the events o f reaction ( I ). In the sample used for the analysis of the K - n " scattering, where the f o u r - m o m e n t u n l transfer to the Krr system is small, the fraction of ambiguous events a m o u n t s to 16.6%. The solution of the kinematic fit with the lowest ×2 has been retained. The influence of the X2 choice on the results of the elastic K - rr- scattering cross section and phase shifts is negligible.

384

B. Jon~elans et al.. I = ~ K -rr- elagtic scattering

Our analysis is based on a sample of events with the four-momentum transfer squared falling reside the inter~,al

(-tK- - K - r r - ) m m <

-tK--

t

'~

K - n - <0.4(GeV.c)'.

(4)

The prr" effective mass spectrum or" tile full sample for reaction ( I ), as well as of the sample witil the restriction (41 is shown in fig. 1. This figure shows that reaction 1'2) is indeed dominating. 2.2. The extrap,,lati, m ]i)r the elastic cross st'cti,,n Tile experimental differential cross section of reaction ( I ) has been related to tile on-mass-shell K - rr elastic cross section by tile follov.'ing equation (rcf. [I 71): ,

64C rt- k-.~

(t.-ta2) 2 33o ' I "~ ¢1't.m. M-) Om-O l ' 3 t

='1K-

"

-1'm) Ol'"~(~l)+ ~

A 1.re.M)

× (t - u2) ''.

(5)

I!q. (5) is a straightft~rward c~msetluence of lhe conventional Chew-Low theory. The symhols have the tollowitlg meaning: k is tile nlolnentunl t~t"the inctmfing K - in the c.m.s., s is the square of the total energy ill tile c.m.s., t is the square o f the four-lnt)lllenluul transfer I'rom the inct)ming K to the K -rr system. /..t is the mass o f the pion. gpn. is the cross section o f the on-mass-shell elastic prr* scattering. o K _ , _ is the cross section of the on-mass-shell elastic K - r r " scattering, ,,In(re,M) are ct~el'ficients o f tile expansion series, and

¢(t.m,M) = &

- (M-mp)2)(t -(M + mp)2)(t-(m-mK )2)(t

- ( m + m K )2) .

(6)

The factor C = 0.3,q9 takes care of tile units ch~sen. Op,,~. depends on the effective massM of tile wr + system. It was obtained by interpolation, from tile experimentally well known values for tile n*p elastic scattering cross section ('ref. [18]). OK - n - depends on the effective mass m of tile K - r r - system. In order to determine o K _ • - from the experimental data a maximum likelihood method was used as described by Linglin (ref. [ 191). For the construction of the likelihood function the expansion series of eq. 1'5) has been broken off after tile second term. Tile coefficients A I and A 2 and o K _ ,r- appear as free parameters. Only events obeying both condition (3) and (4) have been used in the analysis. We checked that varying the intervals for t and M does not significantly alter the results. Tile resuhs for o K _ , - as a function of the K - n'- effective mass (m) are shown in fig. 2 and table 2. In order to verify the resuhs, the experimental distributions o f M and t are compared with the predictions o f e q . (5) after introducing the param-

B. J o n g e / a n s er al . I = ~ K - n - e l a s t t c

385

scattering

(m,,) 4o~

00"

Q6

-

-

•

'

1o

. . . . . . 1,4

mK-.-COeV/c 2)

Fig. 2. The elastic cro,;s secnon o K _ " . in millibarn~, a~ a function of the K - - - effective mas'~. Tile errors arc stati,~tical. Table 2 °K -~r " in mb depending on m K n_

I

_

mK-n

-

(GeV/c 2 )

number

o K_n_

of

(rob)

a)

evt'rtt S

< 0.7 0.7 0.8 0.9 1.0 l.I 1.2 1.3 1.4 -

0.8 0.9 |.0 I.I

1.2 1.3 1.4 1.6

103 345 424 407 444 318 211~ 141 78

1.3 2.8 3.3 3.1 2.8 2.n 2.1 2.1 2.3

-~0.4 ~ 0.4 I 0.4 t 0.4 t 04 eL4 t 0.4 t 05 t 0.6 t

a) "l'hc errors arc statistical.

eters resulting from tile likelihood fit (figs. 3, 4). These figures show that the M and t distributions are well described by eq. (5). The agreement in tile t distribution may be interpreted as an a p o s t e r i o r i justification for the fact that no explicit form factors are used in eq. 5. The results are also in reasonably good agreement with o t h e r results o f tile K - r r elastic scattering cross section (refs. [ 7 - 1 I, 14, 16]). For the highest m K _ , region it must be kept in mind that the distance in t to the pion pole is larger than 0.2 ( G e V / c ) 2 . The background present in tile sample o f events obeying the conditions (3) and (4) is due to the final states producing directly or indirectly K*(890) ° ( a p p r o x i m a tely 30'7,, o f the sample). O t h e r background processes are negligible in tile chosen sample. It has been verified that background subtraction alters the results only within the errors. We prefer to present tile resuhs for o K _ , _ w i t h o u t background subtraction.

386

B. Jongelans et al.. I : ~ K - n - elastic scattering m K-if-cO 8

og(, m K-I~-
08
60

~"

40

> :E 0

20

i i

i

oa

;

i.'1

i i i

I-.-

1

z I.d >

60

Iz. 0 o:

I.,U

40

'

~

'

i

i

:

i

[

1

444

424 L

;

I..-

,, i

I

J

11( rnK- 1T-<12 12( m K- 1~-<1 3 13(inK-if-<1

4

i

I[ z

i I i

20

i

14

125

136 114

1;~5 •" M p r t ÷

13J6 114

125 136 114

(GeV/c

125

136

2)

I Ig. 3. The eftectlve pn nla.~ dlqrJbut~on In tile region 1.14 < ,t.f,.~,.,~.< 1.36 f,eV/c lot event,~ v, ilh lt~w four-motnentum Iran,;ter .l K " - K -n - < 0.4 IGe~ie)" in tile different regions of tile K - n - effective ma~'~. The hi,;togram rcpresent~ Ihe experimental data. The curves drawn arc the prcdiclit~n,~ with the be~! I'll parameters in,erred in formula 15) for n running up to 2. In uaeh |ll,;togran| Ihe tolal nunlher of evenI,~ is al,;o given. 2.3. D e t e r m i n a t i o n o f t h e p h a s e shi]'ts o f t h e K - rr - elastic s c a t t e r i n g

T h e phase shift analysis has b e e n d o n e using the K - n - elastic cross section as f o u n d in the p r e c e d i n g section a n d the e x t r a p o l a t e d values o f the spherical h a r m o n i c m o m e n t s o f the d i s t r i b u t i o n o f t h e angles b e t w e e n the i n c o m i n g K - a n d tile o u t going K - in the K - n'- s y s t e m . T h e s- a n d p-wave phase shifts have b e e n d e t e r m i n e d u n d e r t h e a s s u m p t i o n t h a t the inelasticity m a y be neglected. For on-,nass-shell elastic K - n ' - s c a t t e r i n g the differential cross s e c t i o n m a y be w r i t t e n as:

do _ 4.

d~?.

q2

+ I

~= o

2i--7-----

'

(7)

387

B. Jonge/ans et al.. I = ~ K - ~ - elastic" scattering

mK-tt-<08 120

O9
R-" % (3 0

0

1.0< r n K - R - < l 1

08( rn K'ff" ( og

80

6o

!

40

U~ I-

z

bJ ;>

20

i t i

bJ I,L 0

i

n,bJ

i

407

]

1

i

i J

,

I 1.1< mK-~-<12

m

60

Z

1 I

1.3< rr'tK- 1T- { 1 4 14~ inK- IT.-< 1 6

12( inK- 1~-<1.3

r

40 i

F 20 318 L, 0

2

218

i .4

L . - - ~

0

2

- -t

4

t__ o

.2

4

2

4

( G e V / c 2)

Fig, 4. Same as tlg,. 3 bur n o w ~ho~.ing the +Xl)Crimcntal distribution,+ of and the predictions for

-tK~

K-n-"

where q is the m o m e n t u n l o f tile K - meson in the K - n rest s~:stem, f~ tile orbital angular m o m e n t u m : Y~)('0)'s are the spherical harmonics and 8~J , s the I = l-I phase shifts. The angle 0 is the angle between the incoming K - and outgoing K - in the K - n - rest system.

B. Jomtt'/ans et al. I = ~. K-.-

388

elastic scattering

010

010

°°}ff

f

O~ t

080 -Og~

063-080



I

m K-~-

t~O - 1 2 5

0 9 5 -r~o

(GeWc') -01~

-olo

0~0

L

t-.t

010

ti.

OIX .

t .

-OK 0oo

f

....

0~)



o,4o 000

o,'o

Q~

o4o ouo --t K'--"

o,~o

0,6o 0oo

o~o

040 olo

K-~-(GeVIcY

'a:,C,,~,,',:::,~,,,,:,,;;:;','L~; L!;I,,::',:Z,nI ,,~;,:~.",:;,:,';:',,,::',-,:~';/:','::'~:,i~::'~:,~;:',',,:'~,,,~I' ,,~, ; a~ocLitcd

errors

;.ire al~,o

~ivcn.

I|" we asstlllle that only s- alltl p.w;ives contribute to the K - ~ " elastic scattering at low values o f m K . rr - we obtain the following equations:

OK -n

-

4rr ~ . ~ ~ = - - ( s i n 26 + 3 s m ' 6 ), q-

(8) (Y~)=

~-

3 (Y2))-x,,~' --

sin 2 h3Q+ 3sin 2 h~ 3

sin'8 I

sin2h3+3si,.l 2 63

I

From the eqs. (8) it is clear thai tile observable quantities are invariant under a simul. taneous change in sign o f , ~ aml h~. Moreover. adding 180 ° to both these solutions does not alter the observables either. It+ this study we can only determine the relative sign ot",53 and ,~p and we only quote the values in the neighbourhood of O°.

8. Yongclans et al.. I = ~ K - . - elastic scattering

389

The phase shifts 6 3 and 6~ have been determined in four regions o f m K _= _ (see table 3). The extrapolation of tile m o m e n t s t o tile pole has been done with a linear function in (t - / 2 2 ) over the region It' < 0.4 (GeV'c) 2. A quadratic extrapolation function gave errors twice as large on ( Y~ ) and ( ).~l_ ) as the linear one. but did not alter tile results for the phase shifts. In fig. 5 we show the behaviot, r of the moments as a function o f t and also tile extrapolated moments in four different m K - , _ regions. With these extrapolated values and tile cross section o K . "3- as given in the preceding section we performed a IC fit for the variables 6 3 and ,51 using the formulas (8). in table 3 we show the results obtained for the fitted values of tile phase shifts. and their corresponWe also summarize tile inpnt values for O' K . . ' " ( ) .rlI ). ().~l) . ding values calculated from tile fitted phase shifts. In figs. 6 anti 7 we show I,~i]l. 1,571. and (Y/). ( yll> for tile four mass intervals, tip :o the mass region 0.05 < i n K _ , < I . I 0 (,eV/c 2. 16hi increases tr~ml 5.¢~ to 16. () . F o r l . l O < m K _ ._ < GeV/(.2 the s o l u t i o• n w i t h 1 6 6~,1 -_ .•. . ,o has tile h~v,e,ct ~ - . I l o w e v e r , the o t h e r •

-

]

.

c~

n

solution w i t h 16~[ = 17. I ° continues tile observed increase. Tile values of I,~,~1 are low in the first three mass regions. In the fourth mass region 16 ~1 becomes larger 20"

,

,

1

18o'1 10"

o"

o' i

|

*

i

I

O6

|

~

10

m.-..

.....

I

0 i

st . . . . I

i

06

lJO

(GeV/c 2)

rex- ~ .

(GeV/c 2)

I-ig. 6. The pha,e shlfh ~,; and 6i * as a function o f m K - n _ .



02

O~

06

'

10

O0 06 inK- ~(OeV/c0

++ 10

Fi~. 7. Behavi,~ur o f the extrapolated value~ o f (hc experilnenta] ii1(111|cI3t%(YIl)) and (}'~)) a~ a functi,,n o f i n K _ " _ Iogctht'r v, ith the v;ihlc~, ohtaincd in the fit (triangle,,). rhc valu¢'~ obtained with the ~ecl}nd '~*lluticm arc drav, n v.ith d,qted trian).:le,..

390

B. J o n g e ] a n x e t al . I = T K -~t - e l a s t w s c a t t e r i n g

%

r ~c v v

--

r~

-f

~

~

~i

r~

c~ - I

I

v

"Jr

0

e.,-. -_~-z v

3~

m

•

V

r'~O

ca V .~

"

~

.

~

°,

~

. . . .

I

e.[

'~

E

. ~

I

.o ¢-

E

,.a~.l G

~.

~

"1"

~1 e'l

I

eo

,.-.

~a r. A II It:

E

I

z 0

Z

~.

~

~

~

~

"0 ~a

B. Jonge/ans et al.. I = ~ K - = - elastic scattering

39 I

than 1631 in the solution with the lowest ~(2. The other solution has 15~[ < [h301. For the highest mass regions the probabilities for the fits are only at the percent level. The analysis for the two higher m K - ,r - regions was repeated allowing for the presence of a d-wave. In this case also the extrapolated moments
3. A discussion of the results 3.1. T h e OPI:" m e c h a n i s n z

We first give the experimental evidence supporting the one-pion-exchange mechanism. In tile preceding see,ton we used the moments ( YI0 ) and (Y~) for the analysis. For unabsorbed one-pion-exchange the m :/= 0 moments should be zero. Table 4 shows the real part of the extrapolated moments with tn :¢=0 for ~ = I and 2. The experimental values are zero within the errors.

392

B Jo,tgtTan~ er al.. I -- ~ K - , -

elastic s c a t t e r i n g

Table 4 l-xperimental values ,ff the extrap,)lated m o m e n t s d e p e n d i n g t~n lhe a,'lmUthal angle ¢ at the K - r r ',¢rtcx J) -;K_

_tt;t.V'c:)

11.63

OSt~

()~t)

0.95

-0.q5

- 1.10

1.10

- 1 25

Re Y I

().1"118 _* (1 (11,q

11.~114 .,. ()(118

(.I.017 t 0.02(1

D r i l l -" 0 . 0 3 0

Re ~'~

0.021~ : 0 h l q

0nh,q .-- 1) 01,~

- 0 . 0 0 1 - 0.{323

00.13 _- 0.Q36

Re )'i

-flll()l _. 11.017 -f~.nl2 : 0.1)17

- 0 . 0 1 2 -. (L019 - n 013 -. 0.029

a) T h e ,c .m.~le,, t)t" tit,." (;ottt'ricd-l.wks-n ,<.~~tem are u'~ed.

q.

uo

'q

¢,1

.5

.4 .3

.2 .1

0

-,2

.4 .3 .2 ! .1

15

10

210

Mp.. (GeV/d) I ig. x. T h e hchavit~ur ,)l" the m o m e n t s
The one-pit>n-exchange fig. 8 w e s h o w t h e m o m e n t s

n ~ e c h a n i s m c a n a l s o be v e r i f i e d at tile b a r y o n (Y l°>p a n d (Y~>r, at t h e b a r y o n

-t < 0.4 (GeV/c) 2 but without

conditions

v e r t e x . In

vertex for events with

o n ttl K - n -" T h e r e l e v a n t a n g l e 0p is n o w

393

B. J o n g e l a n s et al.. I = ~ K n " t'lasttt" scattering

the angle between tile target proton and the outgoing proton in the prr" rest system. Our experimental values of , 2 p follow the expected values rather well. but those |'t:r (l'";)t:, fail to produce the characteristic change of sign at 'llp,,, = 1.25 GeV,:c 2. Contrary to what was found in ref. II 51 the extrapolation of m o m e n t s did llot improve the situatiou. Tile positive value of ( )'"l~v corresponds to an excess of positive values of cos 0p. It is well k n o w n that tile final state ( 1 ) is densely populated with so called Q events ( 1.2 < m K - • ~ , _ < 1.5 G e V / c 2 ). An a t t e m p t to suppress these events (ret. lSl ) did not yield an improved behaviour of (YI°)p at tile baryon. vertex. This partial inadequacy of ()"~;) It) folhv.v the on-mass-shell behaviour asks tt.)r some caution with respect to the validity of the simple OPE model used in this anal.vsis.

3. 2 . . . l

c~,~lparis, ,n with

r~ther e.rperi, le, ls

B.lkker (ref. Isl) has determined 8~ and 81 ill Kn scattering from the reaction "{ K n ~ K " tr p. Our results essentially agree Wlth Ills data. All increase of Dill to 15" follow¢d bv. a decrease to .~° at -I K .rr - ~ 1.1>" (,eV, " ' c-.' Tile value t~t" 18]~'Its" very sluall ~ I o except a t m K tt ~ 1.15 ( ; e V / c 2 w h e t e t S i"~I j u. t u p s t o I i o. I11ingh;.i,nel al. (ref. [I 51) detcrnlincd 8:j in tile K~'n -'-- K ~ ' r r and K+rr Kg~rrn scattering processes which are doluinated by I = ~ v.avcs. One of their st)lu. tious has 18i~jlvalues that ;.ire com[~atil~le will, ours within their somewhat larger •

.

errors.

4. Conchlsions

('i) Our d;ita show th:,t the K n elastic cross section lies between 1.3 and 3.3 1 . 6" G"e V h ' - . ~ with a mean value o f . "~ . 5 nlb. for Ill K n . ( (ii) The behaviour of tile tliffcrenti:d cross section d ~ f f d t for tile reaction (2) is very well described by the formula (5), using the fitted parameters and an expansion series of order 2. (iii) Tile values of tile phase shifts 83 anti ~ of K n elastic scatterin~ start with 1831=6" rising to 17 ° a r m K_ _ = 1 . 0 3 G e V / c 2 . A t m t,_n_ = I . I g G e V / c 2 there are two solutkms tot 18t)I, one around 2 , the other a r o u n d 17 . The values for I~ ~1 start at 0 ° and rise to 10 °, but at m K - , - = I. I g GeV/c 2 there is a secoiid stflution with 16~ ] = 1.5 ° . The essential point is that we certainly need a p-wave ctmtribution It) explain the experimental data. (iv) A way of determining whether tile rather poor representation of the moments of tile K - t r - system above t/.i = 1.0 GeV/c 2 by an s-wave and p-wave approximation is due to background processes or due to f u n d a m e n t a l l y different processes that lead to the final K - n - state would be to repeat this analysis at higher incident K - m o m e n t a . Ill[)

•

3

o

o

394

B. Jongelans et at.. ! = ~ K - n - elastic scattering

We are i n d e b t e d to the o p e r a t i n g crews o f the C E R N p r o t o n s y n c h r o t r o n a n d 2 m C E R N h y d r o g e n b u b b l e c h a m b e r a n d t h e c o n s t r u c t o r s o f the m 6 b e a m . We appreciate t h e c o n s t a n t e f f o r t s o f o u r s c a n n i n g , m e a s u r i n g a n d c o m p u t e r staff.

References [1] II.G.J.M. Tiecke et al., Nucl. Phys. B39 (1972) 596. [21 R. Blokzijl et al.. Nucl. Phys. B51 (1973) 535. [3] B. Jongejans and I1. Voorthuis. Amsterdam-Nijmegen Collaboration. Paper submitted to the 15 th Int.Conf. on high energy physics, Kiev. 1970, Abstract Session 4C No. 12. [41 B. Jongejans and ti. Voorthuis. Amsterdam-Nijmegen Collaboration. Proceedings of the first EPS conference on meson resonances and related electromagnetic phenomena. Bologna, 1971, ed. R.H. Dalitz and A. Zichichi (Ed. Comp. Bologna. 1972) p. 57. [51 II. VoorthiJis, thesis 1973 Amsterdam. [61 E. Urvater et al.. Phys. Rev. Letters 18 (1967) 1156. [7] Y. Cho et al., Phys. Lettet,~ 32B (1970) 409. [81 A.M. Bakker el al., Nucl. Phys. B24 (1970) 21 I; A..M. Bakkcr, thesis 1972 Amsterdam; A.M. Bakker, SABRE Collaboration, Proc. of the I,~t EPS conference on me,on resonances and related electrom:,gnetic phenomena. Bologna, 1971 ed. R.II. Dalitz and A. Zichichi Ed. Comp. Boh~gna, 1972) p. 53. 19] P Antichctal..NucI. Phys. 1129(1971) 305. I IO] A.R. Kir~chhaum et al.. Phys. Rev. D4 (Ig71) 3254. [ I I ] C. Brankin et al., Contribution to the Am,~terdam Int. Conf. on elementary parttcle't. June 1971. [121 II. Yuta et al.. Phy,~. Rev. Lettcr'~ 26 (1971) 151)2. 1131 R..~lerccr et al., Nucl. Phy.~. 1132 1'1971) 381. [ 14 ] "1".(;. Trippe. I.BL 763 I)ecemher 1971 (unpubli,~hcd). [15] I1.11. Bingham et al., Nucl. Phys. 1141 (1972) I. [161 D. l.inglin et al., Nucl. Phys. B57 (1973) 64. [171 J. Nai,~se, Intcrn:,l report 11)8 l.IHIIl.~, (Brussels. March 1968). W. de Bacrc et al.. Nucl. Phy,~. BI4 (1969) 425. [ 181 (;. Giacomelli, ('H;,N Ill IRA 69/I. [ 191 1). Linglin. the~i,~;CI.IRN/D.PII II/Phys. 69 .34 (1969). [2111 Rutherl'ord-Iicole i't~lytcchntque-Saclay ('ollahorati~m, Contribution to the 2nd Aix-enProvence Int. Conf. on elementary p:trticle,~, 1973, No. 226.